This invention concerns a new chemical process for making aromatic ethers. Ethers thereby obtained have various uses, for example, as chemical intermediates, as heat transfer media, and as herbicides. Polymeric ethers preparable by this process are useful moldable plastics.
A common conventional method for making aromatic ethers involves the reaction of a metal salt of an aromatic hydroxy compound with an alkyl or aryl halide. Alkyl sulfates and sulfonates can also be used as alkylating agents in this kind of reaction. In some cases, a phenol can be reacted with an alcohol in the presence of a strong acid to produce the alkyl phenyl ether. In all of these conventional methods, the reaction mixture is either basic or acidic and contains an inorganic impurity, i.e., a metal salt or a spent acid which must be separated from the ether product and discarded.
It is known that phenyl alkyl carbonates can be thermally decomposed to form mixtures of products including the phenol and the phenyl alkyl ether. However, the decomposition is slow and usually incomplete and requires high temperatures or long heating times. The decomposition of cyclic carbonates such as ethylene carbonate and propylene carbonate to form ethylene oxide and propylene oxide respectively is known to be catalyzed by sulfonium and phosphonium salts and some metal salts (see Wu, U.S. Pat. No. 4,069,234).